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Hazelnut Hertitage

One hundred years ago, George Dorris, a lawyer turned farmer, knelt in the soil between the confluence of the McKenzie and Willamette rivers and planted five acres of hazelnut trees. Dorris’s trees were the first commercial hazelnut orchard in Oregon.

With that orchard, Dorris planted the state’s hazelnut industry. Over the years, he planted a dozen more orchards and established a hazelnut nursery that operated for 40 years and produced about 70,000 trees per year.

Today, about 650 Oregon families grow hazelnuts commercially on 28,000 acres throughout the Willamette Valley. It’s estimated that more than half of those trees came from Dorris nursery stock, according to Oregon State University Extension horticulturist Jeff Olsen.

“There’s been a lot of progress in the industry,“ Olsen says, “but what was done with hazelnuts at the Dorris Ranch formed the starting point for where we are today.”

And today, Oregon accounts for 99 percent of the hazelnuts grown in the United States and is the third largest producer of hazelnuts in the world, behind Turkey and Italy.

The state’s harvest of hazelnuts, which are also called filberts,
averages more than $30 million in farm gate sales. Hazelnuts have found their way into a distinctively
Oregon cuisine. Dipped in rich chocolate, crumbled over a fillet of wild Oregon salmon, or munched whole and washed down with an Oregon microbrew, hazelnuts add flavor, crunch and a nutritional boost to snacks and recipes.

Hazelnuts are easy to love, but they are not always easy to grow. In the 1970s hazelnut growers in southwestern Washington discovered a fungal disease had gripped their orchards like a tourniquet, forming cankers that were slowly girdling branches, limbs, and trunks before killing the host trees. It was eastern filbert blight. Spores carrying the blight travel easily in the wind and quickly contaminated entire orchards. By 1986, the blight struck the north end of the Willamette Valley.

Hazelnuts emerge from a frilly husk, then drop to the ground for harvest. Photo: Lynn Ketchum

Hazelnut harvest can be a dusty job, as fallen nuts are swept from the ground in an explosion of leaves and twigs. Oregon growers produce 99 percent of the nation's hazelnuts. Photo: Lynn Ketchum

Since then, several hundred acres of Oregon orchards have been affected by the blight and thousands of trees have been lost. Expensive fungicides and intense pruning of infected branches can slow the spread of the disease, but once a tree is infected, it will likely die.

However, certain varieties of hazelnut have an inherent partial resistance to the blight. This disease resistance has been of particular interest to researchers at Oregon State University’s Agricultural Experiment Station and their colleagues at the U.S Department of Agriculture. C.E. Schuster began the hazelnut breeding program more than 80 years ago by amassing a large volume of work on the hazelnut variety Barcelona, the most common commercial hazelnut grown in Oregon. By 1969, when Maxine Thompson took over the program, Oregon was ready for a new variety of hazelnut—one more suited to the kernel market and capable of selling for a premium price on the world exchange. Thompson worked on several crosses that would eventually be released as named varieties and began the journey toward a nut resistant to eastern filbert blight.

OSU horticulture researcher Becky McCluskey happily sorts through the results of 20 years of research: the Santiam hazelnut that is entirely resistant to eastern filbert blight. Photo: Lynn Ketchum

Since Thompson’s retirement in 1986, Shawn Mehlenbacher has pursued the goal of creating new, high-quality, highly productive hazelnut varieties that are completely resistant to eastern filbert blight. Recognized as a leading expert in hazelnut breeding, Mehlenbacher has traveled to Europe, Asia, Turkey, and the former Soviet Union to collect new genetic material to use in his breeding program. Much of this genetic wealth is archived at the USDA Germplasm Respository in Corvallis. Building on this vast genetic resource base for hazelnuts, Mehlenbacher’s program plants and evaluates 4,000 to 6,000 seedlings per year.

“With every new progeny, or seed lot, that we plant, we get one or two interesting trees,” Mehlenbacher says. “Likewise, with each new parent used in the program we save very few seedlings. Resistance is almost always coupled with something you don’t want. It’s not a quick process.”

During the last 19 years, Mehlenbacher has had several incremental successes. In 1997, he and his team released the variety Lewis; then in 1999 they released Clark. Both cultivars have several traits desirable to the industry, and both are moderately resistant to blight; however, they are not completely immune. It wasn’t until last winter that Mehlenbacher released a variety completely resistant to the disease and of similar kernel quality to Barcelona.

Called Santiam, the new variety is an early maturing hazelnut with high yield efficiency, thin shells, and good-sized kernels. And it is entirely resistant to the blight. Mehlenbacher says orders for the trees are already backed up more than two years.

“Growers need something to plant now because their orchards are dying,” he says. “We’ll be releasing newer, better things as we have them, but right now Santiam is a good option.”

Mehlenbacher is currently developing additional blight-resistant varieties with good kernel quality that can act as pollinizers for Santiam. Because hazelnuts are self-incompatible, orchards include a main crop variety and a minimum of two compatible pollinizer varieties with significant genetic differences.

“One of our goals is to develop a variety worthy of a premium price on the world market,” Mehlenbacher says. “There is a variety from Italy that receives a 50 percent higher price than the Turkish standard. We can easily get a 25 percent price increase.”

In order to get more Oregon hazelnuts on the world market, growers must first get trees into the ground, and propagating adequate numbers of trees in a short time can be a challenge. Traditional methods of propagation like layering and grafting are slow and not always successful, so many nurseries and growers have begun incorporating trees produced through micropropagation, the process of growing plants in tissue culture.

“With tissue culture you can achieve the same multiplication rate in a month that you would normally see in a year using conventional methods,” says Bill Proebsting, a professor in OSU’s horticulture department and a specialist in woody plant propagation. “In principle, we can grow up to 100,000 plants from one shoot in a relatively short amount of time.”

The researchers establish cultures of clones before they release new hazelnut varieties, then they distribute 20 to 50 plants at a time to commercial micropropagation facilities. These commercial facilities continue the multiplication process, bulking up their supplies, before selling to growers.

“We’re a trusted source,” Proebsting says. “Commercial sellers know the identification is right and that the stock is clean.”

Many of the state’s mature orchards, like those on the Dorris Ranch, continue to be at high risk for blight. In the northern part of the valley, entire orchards have been lost to eastern filbert blight, and the disease has been found as far south as Springfield. The appearance of blight-immune varieties like Santiam provides growers who have been affected by the disease with an incentive to continue planting and selling hazelnuts. However, it takes about four years from the time growers plant a young hazelnut tree for the tree to begin producing in economically harvestable quantities.

“It’s encouraging to see what the breeding program is coming out with,” says Olsen. “The people who have been struggling with blight in the business are certainly ready to move forward with the new varieties. This is what we’ve been working toward for the last 20 years.”

SWEET!

Oregon hazelnuts are a key ingredient in some of the Pacific Northwest's finest cuisine — and newest products. Fresh hazelnuts, purchased directly from the grower, add a nutty, sweet flavor to Vibrant Flavors® Oregon Dukkah. Donna Dockins commercialized this nut and spice mix with help from OSU's Food Innovation Center Experiment Station, the only urban agricultural station in the nation.